Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a novel anticancer agent for glioblastoma multiforme (GBM). Some GBM cell lines, however, are relatively resistant to TRAIL. Doxorubicin (DOX) can sensitize GBM cells to TRAIL-induced apoptosis, indicating that the combination of DOX and TRAIL may be an effective strategy to kill TRAIL-resistant GBM cells. However, the therapeutic effect is limited by the short serum half-life of TRAIL, chronic cardiac toxicity of DOX, multidrug resistance (MDR) property of GBM cells and poor drug delivery across the blood-brain barrier (BBB). To solve such problems, combination treatment of TRAIL liposomes (TRAIL-LP) and DOX liposomes (DOX-LP) were developed for the first time. The in vitro cytotoxicity study indicated that DOX-LP sensitized GBM cell line U87MG but not normal bovine caruncular epithelial cells (BCECs) to TRAIL-LP-induced apoptosis, demonstrating the safety of the combination treatment. This sensitization was accompanied by up-regulation of death receptor 5 (DR5) expression and caspase activation. Furthermore, the combination therapy of TRAIL-LP and DOX-LP displayed stronger anti-GBM effect than free drugs or liposomal drugs alone in vivo. In summary, the combination treatment reported here showed improved therapeutic effect on GBM. Therefore, it has good potential to become a new therapeutic approach for patients with GBM.
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